Harry explained he chose to include two diamonds from Diana’s personal collection “to make sure she’s with us on this crazy journey.”

“It is days like today when I really miss having her around, but with the ring and everything going on I’m sure she’s with us, jumping up and down somewhere else,” he said.

Meghan, who was introduced to the prince through a mutual friend, was clearly touched by the gesture.

Meghan Markle's engagement ring is a touching tribute to the late Princess Diana. (AAP)

“Everything about Harry’s thoughtfulness and the inclusion of [the diamonds], and obviously not being able to meet his mum, it’s so important to me to know that she’s a part of this with us,” she explained.

“And I think in being able to meet his aunts and different people who are so important to his mum, I’m able to in some way know a part of her through them - and of course, through him.”

The Duke and Duchess of Cambridge, their neighbours at Kensington Palace, had been “longing” to meet Harry’s girlfriend from the moment they found out about her.

“Catherine’s been absolutely amazing, as has William as well, fantastic support,” Harry said.

WATCH: Prince Charles responds to his youngest son's engagement news.

Meghan has also shared “a handful of teas and meetings” with Harry’s father Prince Charles and Camilla, Duchess of York at their Clarence House residence.

She described the experience of meeting Queen Elizabeth for the first time as “incredible”.

“To be able to meet her through his lens, not just with his honour and respect for her as the monarch but the love that he has for her as his grandmother, all of those layers have been so important for me,” the TV star said.

Meghan Markle described the Queen as an "incredible" woman. (Getty Images)

“When I met her I had such a deep understanding and of course incredible respect for being able to have that time with her. She’s an incredible woman.”

Harry said his grandparents had provided “absolutely solid” support throughout the relationship.

“They’ve known for quite a while, how they haven’t told anybody is a miracle itself,” he quipped.

Prince Harry says his family has provided "solid support" to him and Meghan. (AAP)

Perhaps the most important stamp of approval came not from Her Majesty and the Duke of Edinburgh, but their beloved pets.

“The corgis took to you straight away,” Harry remarked to his fiancee.

"I've spent the last 33 years being barked at; this one walks in, absolutely nothing … just wagging tails,” he joked.

WATCH: The engagement announcement came on Monday morning.

"[They were] just laying on my feet during tea, it was very sweet," smiled Meghan.

Prince Harry and Meghan Markle’s engagement was announced in a statement from Clarence House on Monday morning.